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Publication Type: search.filters.UBSTyp.DissertationStart date: 2020Subject: search.filters.subject.500Subject: search.filters.subject.620Institute: search.filters.UBSInstitut.Institut für Bioverfahrenstechnik

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    Scale-up of gas fermentations : modelling tools for risk minimisation
    (2020) Siebler, Flora
    The reduction of greenhouse gas emissions is a global endeavour supported by society, politics and industry. In recent years, circular economy, reducing the exploitation of fossil energy sources, have increased the demand for new solutions when producing commodities and fine chemicals. Caboxydotrophic fermentations with acetogenic bacteria are potential processes in order to reach these goals. They convert gaseous substrates such as CO, and CO2/H2 mixtures. However, gases as sole substrate are rather challenging, not only in small lab-scales but especially in large-scale. Transferring an efficient fermentation process from experimental to industrial scales often results in unpredictable performance losses. This study presents an in silico concept minimising possible risks in gas fermentations up-scaling. First, the economical feasibility of various fermentation methods is investigated. Then, two computational tools are presented using Clostridium ljungdahlii as model organism and synthesis gas as substrate in a 125 m3 bubble column reactor. The combination of economical investigation with modelling tools show high potential for successful scale-up of gas fermentations. With this concept feasibility, reactor design, operation mode and general risk minimisation can be analysed and specified.
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    Investigation of the impact of different scale-up dependent stimuli on metabolism and population heterogeneity in Corynebacterium glutamicum
    (2024) Eilingsfeld, Adrian; Takors, Ralf (Prof. Dr.-Ing.)
    This thesis investigates the impact of elevated carbon dioxide levels on population heterogeneity in Corynebacterium glutamicum, a widely used industrial production host. Through a series of experiments involving cultivation at varying CO2 partial pressures, flow cytometry, and analysis of DNA content, the research reveals that increased CO2 exerts significant selection pressure, affecting growth rates and cell aggregation tendencies. Key findings indicate that higher growth rates speed up DNA replication levels, while elevated CO2 levels slow them down. The results contribute to understanding how CO2 influences population dynamics, providing insights for optimizing industrial bioprocesses and support Corynebacterium glutamicum as a robust production strain.